JPS63114967A - Substrate treatment apparatus - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion implantation apparatus for a substrate, and more particularly to an apparatus for implanting If<ions into a silicon wafer.

The process of injecting cations such as boronic, phosphorous, molar, nitrogen, arsenic, and antimony into silicon wafer substrates is an important step in the manufacture of semiconductor devices. An ion beam is implanted into the wafer to embed atoms on or below the surface of the wafer, thereby controlling the electrical properties of the wafer. Because it has been shown that implanting a high-current oxygen ion beam into a silicon substrate forms a buried layer of silicon dioxide, the ion-implanted wafers were prepared using what is called silicon insulator technology. It is considered useful for manufacturing VLSI.

Conventionally, the acceleration voltage of the ion beam used to form the oxidized buried layer of this scale was 200-400 KE V, and the maximum beam current was 10 mA. Also at least 2×1018
In the case of a wafer with a diameter of 100 mm that requires implantation of crA, the processing time is approximately 10 minutes at a beam current of 10 mA. However, since overheating of the wafer cannot be prevented at this current density, a lower current density is required. In other words, a method of processing a large number of wafers simultaneously to reduce the average current density per wafer is used, but this method significantly increases ion processing time, so silicon-insulator technology has to be used. The manufacturing cost of the depth used has been increased by 1. Therefore, at present, the acceleration M11 is 200-400K[V, and the beam voltage is 100-200K[V].
The development of a one-person device for training is underway. This kind of device requires radiation 12X1018 atoms/cti
can be implanted in less than one minute, significantly reducing the unit manufacturing cost of the chip and making silicon-insulator technology economically viable.

However, the high-performance implantation equipment mentioned above requires an extremely high-power ion beam (20.-50Kwfj);
Difficult problems arose during production, and these problems were resolved by ``Nuclear Instructions and Methods'' (NIJC) by PINIZZOTO.
l,, lN5TR, 8ND HET+1003)
J (1985, Vol. 87-8, Part 1, pp. 261-4). Among the issues, the important ones are
This is the effect of the high power beam on the structure of the implanter itself. In particular - the structure that holds the wafer itself is inevitably in contact with the ion beam, so the impact is significant. Because the implantation time is short compared to the implanter's dosing and depressurization times, hundreds of wafers need to be batched simultaneously, and the wafer holding equipment becomes extremely long and requires a large rotating drum or circle. Wafers are often fixed to a plate. Current medium current implantation equipment (maximum beam flow is 10m)
Even in the case of A), special considerations are required for the design of the wafer holding device and the selection of materials used for components that come into contact with the ion beam)]E
f4 (e.g. [1-s(P,)1.It
Nuclear Instructions and Methods (NUCL ll
l5cho RAND HETHO [1S) J (1985
(See Vol. 86, p. 27). In addition to component damage from the ion beam's radiant heat, a significant problem is the sputtering of ions from the implanter that are implanted into the wafer.
Where Fl! Particulate contamination occurs inside the container. This particulate contamination is typically caused by sputtering of the wafer holding device or by flaking of deposits on the implanter upon contact with the ion beam. This type of particulate contamination, at least a portion of which is deposited on the surface of the wafer, reduces the yield of devices after the processing operation is completed. Therefore, minimizing spatter and particulate contamination is the key to semiconductors! It is an extremely important part of the XI B process, and the production line =
It is well known that a first strike down also depends on solving this problem. The injection device described by Rose (RO8F) et al. avoids heavy metals that easily sputter, such as iron, chromium, and copper, and uses aluminum for all important parts.

However, ``Advances in Electronics and Electron Fixtures'' (ADV, IN Fl, EC) by Wilson (R,G, WILSON)
Ding1tONIC5AND El, [CTR0N PII
YS) J (1980, Vol. 138, p. 45) recommends the use of silicon for ion implantation of silicon wafers since the use of aluminum causes a number of problems. Although this method minimizes wafer damage from sputtered particle deposition, it is not possible to make large rotating drums from silicon.

It is also known technology to make parts of the implanter that come into contact with the ion beam, in particular beam control slits and electrodes, from graphite.

Recently, as a measure to reduce the sputtering effect, a method has been implemented to coat the tool-holding device with materials such as silicon carbide or silicon oxide (for example, Guerra (H, G), etc.
II [l'RRA), Penvenisson Z (v.

Nuclear Instructions and Methods (IIUcL) etc.
R, lN5TR.

8Nl))IET)IODs)J (1985
(see Vol. B6, p. 63), but this type of coating is
This can easily lead to serious contamination of the palms of the hands. Furthermore, it is necessary to reapply the surface coating frequently, and
The pause time of the persona r'I increases.

Accordingly, it is an object of the present invention to provide an ion beam treatment method for substrates, which is characterized by making parts that come into contact with ion beams using materials that reduce particulate contamination of substrates that occurs during ion beam treatment. Another object of the present invention is to provide an apparatus, particularly for oxygen ion implantation of silicon substrates, characterized in that the material used for the component is not damaged by contact with the ion beam. The goal is to provide suitable equipment.

Furthermore, an object of the present invention is to provide an ion implantation apparatus that uses materials that reduce particulate contamination of a substrate and that is easier to maintain than conventional apparatuses.

Therefore, in an apparatus for processing a substrate with an ion beam in a vacuum chamber, at least one of the various parts that come into contact with the ion beam is mainly made of silicon dioxide. Provided by the present invention.

The apparatus of the invention, shown in a preferred embodiment, includes a second element arranged to define an aperture through which the ion beam passes, as well as a second element for defining the ion beam as an object. It also contains the following elements, both of which have silicon dioxide as their main material. - It is clear that several elements themselves define the ion beam.

The silicon dioxide used in the apparatus of the present invention is preferably quartz, but quartz glass can also be used. In a preferred embodiment, a semiconductor silicon wafer is used as the substrate, and the ion implantation device preferably includes an ion beam generator containing positive ions (particularly oxygen or nitrogen).

By making the parts that come in contact with the ion beam from silicon dioxide, the sputtering effects that cause particulate contamination of the substrate are significantly reduced. Since the ions sputtered from quartz or fused silica contain only silicon or oxygen, the sputtered layering of the substrate in the presence of an intense oxygen ion beam is of little concern. Oxygen contamination on the substrate surface was also caused by fi11 during the oxygen implantation process to create the oxidized physical implantation layer.
Although this type of oxide contamination sometimes occurs, it is known that this type of oxide contamination can be removed during the photo-1 tweezing step that follows the implant.
Therefore, oxygen contamination associated with silicon dioxide sputtering is relatively unimportant. On the other hand, sputtered metal deposition is a more serious problem because the metal atoms diffuse deeper into the silicone substrate and are difficult to remove by etching. Furthermore, by making the beam defining components and the averte 17 defining components from quartz or fused silica, contamination of the beam itself by ions other than silicon and oxygen is minimized. Furthermore, quartz and quartz glass have the advantages of a low coefficient of thermal expansion, a high melting point, and an extremely low sputtering rate even when placed in the environment of a high-power ion implanter. Further, since quartz and quartz glass can be procured in plate form and have sufficient mechanical strength, it is relatively easy to manufacture a wafer support device using this type of material.

Due to the above-mentioned properties, silicon dioxide can also be used in implantation devices using ion beams other than oxygen and substrates other than silicon.

The reason why those skilled in the art have been reluctant to use electrical insulators such as quartz for parts that come into contact with the ion beam is as follows.
This is probably because the insulator comes into contact with the ion beam and is charged to a high potential, and this high potential affects the ion beam in unpredictable and desirable ways, such as deflection. In particular, it is thought that there was a concern about the impact on related components such as beam definition or focusing slits. However, in reality, it has been found that the effects of charging are not as difficult to predict, and that these effects can be eliminated through thorough design. Although the reason for this has not yet been fully elucidated, it is assumed that there is a natural mechanism that resists the charging effect caused by ion beam implantation.

For example, at least in the energy range used for the implantation process, the charge loss due to the emission of secondary charged particles is approximately balanced by the charge increase due to the bombardment of the ion beam. Furthermore, the charge accumulated on the quartz surface is likely to be further reduced by electrical leakage (which is known to be considerably larger at the usual implantation temperature of 500-700°C than at 20°C). ). However, in order to substantially neutralize the charge build-up that occurs on the surface of critical silicon dioxide wood parts, it is not recommended to emit an electron beam using a flood gun or heated filament, etc., to bombard the heavy build-up surface. It is within the scope of the invention.

The intensity of the electron beam is adjusted to neutralize the buildup of positive charge. However, this electron beam radiation is usually unnecessary, and it is generally preferable to rely on electrical leakage as a means of preventing excessive charge accumulation. A generally effective countermeasure is to improve the design of affected parts.

For example, in the device of the invention shown in a preferred embodiment, at least one conductor device is provided on the surface of at least one component made primarily of silicon dioxide, the conductor device is held at a fixed potential and the ion beam is It was placed so that it would not be directly exposed to radiation. Although the conductor is close to the component surface, it is shielded from direct contact with the ion beam to minimize charge build-up on at least a portion of the silica wood component surface. The conductor is conveniently made of metal and is placed in a groove cut into the surface of the relevant piece of silicon dioxide wood so that it does not come into direct contact with the ion beam and metal ion spatter is minimized. preferable. This minimizes the distance between the ion beam contact surface and the conductor that maintains a fixed potential, thereby maximizing leakage of unwanted charge. This technique is particularly effective during high-temperature operations on the component concerned, reducing charge build-up to acceptable levels.

The apparatus according to the invention is primarily intended for substrate processing involving semiconductor wafers and includes a rotatably mounted drum, the inner surface of which at least in part receives ion beam radiation during operation. designed to receive. In one preferred embodiment, the inner surface contains a plurality of wafer retaining plates based on silicon dioxide, and the retaining plates are arranged such that only the retaining plates receive the ion beam Ill DI on the inner surface of the drum. It has become.

Therefore, when the ion beam enters the drum on which the wafer is mounted, only the holding plate and the wafer are subjected to Iff'P.

In addition to the wafer holding plate, a wafer mounting device can be installed to hold the wafer. Preferably, the mounting Hf& is also made of silica dioxide rAIll.

As a result, the only objects to be irradiated with the ion beam are the wafer substrate, the wafer holding plate, and the mounting device. A preferred retaining plate includes a plurality of flat rectangular plates mounted inside the drum overlapping each other in the shape of a polygonal prism. The shape of the drum is preferably a truncated cone.

Both the wafer holding plate and the drum also have at least one well-placed hole behind each wafer to ensure effective heat transfer from the wafer to the fixed surface surrounding the drum and maintaining a constant temperature. do. As a result, the temperature of the wafer during the implantation operation can be controlled.

Alternatively, the wafer holding plate may be made of a material that is relatively transparent in the infrared region, so that the radiation by the holding plate provides sufficient thermal contact with the fixing surface. Since the heat dissipation hole described above can be omitted.

Wafer and its support equipment
A good thermal contact between the devices (devices or retaining plates) is usually not necessary. This is because, in a preferred embodiment according to the invention, temperature control is performed by means of a heat dissipation mechanism as described above. Therefore, while the wafer is held in a general position by a simple mounting device during the attachment/detachment operation of the tube, it is sufficient to maintain the wafer in a predetermined position during the implantation operation by the centrifugal force generated by the rotation of the drum. Easy installation equipment made of quartz or quartz glass is sufficient, e.g.
Suitably, a bracket is fusion welded onto the wafer holding plate and the bracket is provided with slots for receiving the wafer. Alternatively, a peg-like support piece having at least two slots is arranged to grip the lower part of the wafer, and at least t31 stops are arranged to support the upper part of the wafer from behind. establish. The slot in the support piece is suitable for receiving the edge of the wafer. A device of this type is described in detail in co-pending British Application No. 8531723, a copy of which is included in the present application file.

A semiconductor processing apparatus according to another embodiment of the present invention includes a rotatably mounted drum having at least a part of its inner surface as an ion beam irradiated area, and a drum mainly made of silicon dioxide. and an attachment device for securing the fabrication tool to the inner surface.

The attachment is such that the apparatus contains slotted brackets or dowels in place as described above, and is mounted directly inside the drum or on a wafer holding plate provided inside the drum. In the case of small children, the wafer holding plate is gold 1i! %j with silicon or silicon monoxide by known methods.

It will be appreciated that the attachment device is the component of the implanter closest to the wafer and therefore the most critical component with respect to wafer contamination by spatter during implantation operations.

Therefore, in some applications, the advantages of the present invention may be fully obtained by using a conventional coated metal retaining plate in conjunction with a silica wood mounting device.

Although the preferred method for maintaining the wafer at the desired Ua is thermal radiation cooling, it is within the scope of the present invention to provide a cooling system for water cooling of the holding plate and one wafer.

Preferred embodiments of the device of the invention will be described in detail below with reference to the accompanying drawings.

Let us explain about Figure 1. An ion beam (1) is transmitted from an ion source (2) to an aperture (25) and an adapter (
4) and enters the vacuum injection container (3). The ion beam (1) typically contains an oxygen ion beam, with an accelerating voltage of 200 mA and an EV1 maximum beam current of 200 mA.

Preferably, a mass filter is applied to the ion photonic ablation to remove ions of unwanted quality m-to-charge ratio. The drum (5) is mounted on a rotating shaft (6) with a bearing (7) containing a rotary vacuum seal to protect the rotating shaft (6) from ingress of outside air. The drive motor (31) for the rotary shaft (6) typically rotates at 120 revolutions per minute. The drum (5) is also shaped like a truncated cone and contains an integral top surface (9), while also having a plurality of branches (8) forming the side surfaces. The upper end of the column (8) is the upper surface (9)
while its lower end is attached to a circular structural member (3
8). Rotation axis relative to the vertical direction (6)
The angle of the drum (5) and the maximum and minimum diameter of the drum (5) are selected so that the column (8) on the remote side of the drum from the adapter (4) is aligned with the axis of the ion beam (1), as shown in FIG. determined to be orthogonal. Both the upper surface (9) and the structural member (38) are water-cooled, and cooling water is guided through a water supply pipe through a rotary water supply device built into the bearing (7). To minimize stress and stress deformation of the drum, heat transfer between the struts (8), the top surface (9) and the structural members (38) is limited to each strut (8).
The holes (10) and (11) provided around both ends of the holder are used to minimize the amount of damage. Therefore, even if the temperature of the strut (8) rises to several hundred degrees Celsius, the drum will not be damaged. Pillar (8)
is preferably made of stainless steel in order to withstand use in 8 gatas. The water-cooled surface (13) is fixed and shaped like a truncated cone and surrounds the outer surface of the drum (5). do. a large area of the surface (13) is attached to the inner surface of the drum (5);
exposed directly to the back of the wafer where the ions will be implanted. A further second water-cooled surface (14) is installed inside the drum (5). Radiation heat transfer takes place effectively from the wafer to the surface (13), (14), and this heat transfer [keeps the temperature to the wafer below the optimum value when the ion beam is operating at the desired power]. That's how it is.

A heater (15) is mounted on the surface (13) and is used for heating to raise the temperature to the required value. Heater (15
) to control the temperature by adjusting the power! Keep value.

A conventional radiation pyrometer 5 can be used to monitor wafer temperature. The surfaces (13) and (14) are the drums (
5) is provided with an aperture for passage without support II. Also, one or more slots are usually provided in the drum (5) which, when in place, direct the ion beam to the cooled beam dump (16).
It gets wet. The beam dump (16) is preferably one with a Faraday cup to accurately measure the strength of the impact beam.

When mounting the wafer on the inner surface of the drum (5), it is done through the insertion port (17), preferably using an automatic mounting device.

The drum (5) has a structure in which a large number of wafers can be mounted at once due to the low cost of wafer ion implantation, and its typical diameter is 1500 mm.

Explanation regarding FIG. 2 follows. The struts (8) are shown in cross section and are generally made of stainless steel with welded lugs (18
). The wafer holding plate (19) contains a flat quartz plate, and long mounting posts (21), also made of quartz, are fused together and short mounting posts (22) are fused together, arranged alternately. be. Both mounting posts (21), (2
2) is provided with a slot for receiving the lug (18). The wafer holding plate (19) comprises alternating long posts and short posts mounted along the inner surface of the drum (5) with overlapping seams as shown. This provides a continuous surface of quartz to the ion beam (1) as the drum (5) rotates. A slot (not shown) is provided in a portion of the wafer holding plate (19) to direct the ion beam (1) into the beam dump (16) when the drum is in position.
). During the ion implantation process, the wafers (20) are fixed to the holding plate (19) by centrifugal force, but when the drum is accompanying, the holding plate (19) supporting the lower part of each wafer is fixed.
9) is held in its approximate position by a bracket (24) fusion welded to it. The bracket (24) is preferably made of quartz and is further provided with a slot that extends along the edge of the wafer. Alternatively, as shown in FIG.
The two peg-like pieces (34) provided in ) can support the dowel. The piece (34) is provided with a slot (35) for receiving the edge of the wafer (20). One or more stops (36) may also be provided, as shown in FIG. The peg-shaped piece (34) and the stop (36) are preferably made of quartz or quartz glass. As shown in FIG. 2, the holding plate (19) is provided with holes (23) located behind each wafer to facilitate heat transfer from the wafers to the water-cooled substrate (13) by radiation. It is possible to support the lower end edge of the holding plate (19) with a stopper attached to the support column (8) so that the stopper is not removed when replacing the holding plate.

Holding plate (19), bracket (24), member (34),
The type of quartz used in (36) is not important; one with poor optical properties is sufficient. It is preferable to maintain purity to prevent sputtering of unnecessary substances. Helaois Co., Ltd. (H
ERAEIIS GHBH) supplied by t6BG or HaBQ
The E variety is particularly suitable.

Figure 3 shows a method for minimizing surface charging due to ion beams. The aperture (33) through which the ion beam (1) passes consists of two silica wood elements (
26) and (27), and both elements are preferably made of quartz or quartz glass.

A plurality of grooves (2) are cut out on the surfaces of the elements (26) and (27) to prevent the ion beam (1) from impacting the bottom of the grooves. Attached to the bottom of each groove is a metal conductor (28) connected to a fixed potential (usually ground). In this device, the distance from the point of contact with the ion beam to the fixed potential is minimized, thereby increasing electrical leakage and significantly reducing the accumulation of unwanted potentials on the surface. The ion beam (1) is connected to the conductor (28
), the beam is prevented from being contaminated by metal ions. This type of avert ↑7 can be used in various places, for example for matching (25) in FIG.

FIG. 4 illustrates the use of an electron flood gun to minimize charge build-up on quartz surfaces within an ion implanter. If a member (31) made of quartz (for example, a T-H holding plate (19)) is unavoidably placed in the middle of at least a portion of the ion beam, the charge accumulation on the surface of the member (31) is prevented by the flood gun (30). ) electron beam (3
2) "c-neutralized. Appropriate method is described in U.S. Pat. No. 3.
507.709.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the injection chamber of the device according to the invention. FIG. 2 is a horizontal sectional view showing a portion of the inner surface of the rotating drum of the apparatus shown in FIG. 1 on which a wafer substrate is mounted during the implantation operation. FIG. 3 shows a device for reducing charge accumulation in some of the components of the device shown in FIG. FIG. 4 shows another device for reducing charge accumulation in a3 of some of the components of the device shown in FIG. FIG. 5 is a side view of the rack support device shown in FIG. 2 for supporting a wafer to be processed within a co-rotating drum of the apparatus. 1... Ion beam 2... Ion source 3.
...Ion implanter 5...Drum 6...Rotating shaft 8...Strut 25...Averti l717
... 1-Ha Oki Entrance Procedure Amendment 4 points January 1986/'? Japan Patent Chief C 1 Indication of the case Patent Application No. 224056 of 1985 2 Name of the invention Substrate processing apparatus 3 Relationship with the case of the person making the amendment Name of the patent applicant Title VT Instruments Group Limited 4 agent

Claims (13)

[Claims] (1) An apparatus for processing a substrate (20) with an ion beam (1) in a vacuum container (3), which includes parts (25), (19), and (34) that come into contact with the ion beam; Device characterized in that at least one of the components is made primarily from silicon dioxide. (2) An apparatus according to claim 1, wherein the ion beam (1
) at least one element (25) arranged to define an aperture for passage through the device. (3) An apparatus according to claim 2, in which at least one of said elements (25) is arranged in said ion beam (
1) A device characterized in that it is arranged to define: (4) A substrate processing apparatus including a semiconductor wafer (20) according to any one of claims 1 to 3, further comprising a rotatably mounted drum (5). , at least a portion of the inner surface of the drum is irradiated by the ion beam (1), and the inner surface contains a plurality of wafer holding plates (19) made primarily of silicon dioxide for mounting the wafers. , further characterized in that the wafer holding plate is arranged such that a portion of the inner surface of the drum that is irradiated by the ion beam contains the wafer holding plate. (5) An apparatus according to claim 4, in which the wafer holding plate (19) includes a mounting device (24) made primarily of silicon dioxide for fixing the wafer to the holding plate. A device characterized by comprising: (6) A substrate processing apparatus including a semiconductor wafer (20) according to any one of claims 1 to 3, further comprising a rotatably mounted drum (5). , at least a portion of the inner surface of the drum is irradiated by the ion beam (1), and the drum is provided with an attachment device (34) made primarily of silicon dioxide for securing the wafer to the inner surface. A device featuring: (7) In the apparatus according to claim 6, the inner surface of the drum contains a plurality of wafer holding plates (19) whose main material is metal, and the mounting device (34) is arranged to hold the wafer holding plates. A device characterized by being attached to the top. (8) In the apparatus according to any one of claims 5 to 7, the mounting device for individually fixing the wafers (20) is arranged to support the wafers. at least 2
At least one stopper (36) is located on the top of the support piece and is arranged to support the wafer from behind.
) and a slot (3) cut out in said support piece.
5) is adapted to receive an edge of said wafer. (9) The device according to any one of claims 1 to 8, wherein the silicon dioxide contains quartz. (10) The device according to any one of claims 1 to 8, wherein the silicon dioxide contains quartz glass. (11) In the device according to any one of claims 1 to 10, at least one of the components (26) and (27) whose main material is silicon dioxide.
the seed is provided with at least one conductor device (28) on its surface, which conductor device is placed under a fixed potential and arranged in such a way that it is not exposed to direct radiation of said ion beam (1); A device featuring: (12) In the apparatus according to claim 11, the conductor device (2) is placed in a groove (29) cut out in the ion beam irradiated surface of the component parts (26), (27).
8) is arranged. (13) The apparatus according to any one of claims 1 to 12, comprising: (a) a generator (2) for the ion beam (1) containing positive ions; The ion beam (1) is produced by making the electron beam incident on the ion beam irradiated surface of the component (31) which further includes an electron beam generator (30) and whose main material is silicon dioxide. A device characterized in that it substantially eliminates the accumulation of positive charges generated on the ion-irradiated surface due to radiation.