Patent Description:
Semiconductor fabrication plants fabricate integrated circuit chips. Many of the processes performed on silicon wafers, such as etch processes, involve the use of a gaseous ambient and often require the use of high vacuum and reduced gas pressures.

Vacuum pumps are used to provide these reduced gas pressures in process chambers, provide chamber evacuation, and maintain flows of processing gases.

Vacuum pumps are coupled to the process chambers by forelines.

A prior art kit of parts having the features of the preamble to claim <NUM> is disclosed in <CIT>.

In an aspect there is provided a modular system of foreline components, which may be connected together to provide a foreline for a vacuum pumping system. The modular system allows forelines to be constructed from standard components.

In a first aspect, there is provided a kit of parts for forming a foreline for coupling a process chamber to a vacuum pumping and/or abatement system according to claim <NUM>.

The first substantially straight end portion, the second substantially straight end portion, and the intermediate portion may be integrally formed.

Each foreline segment is a pipe, conduit, or tube.

One or more foreline segment comprises a respective means for heating that foreline segment, such that heating of each foreline segment is independently controllable.

The kit of parts comprises one or more further foreline segments, each further foreline segment being a substantially straight pipe, wherein the further foreline segments are configured to be attached to the foreline segments, and to each other, so as to form a continuous foreline. Each further foreline segment may comprise a respective means for heating that further foreline segment, such that heating of each further foreline segment is independently controllable.

Each of the one or more further foreline segments may have a length greater than or equal to ten times a diameter of that further foreline segment.

The intermediate portion may have a length greater than or equal to ten times a diameter of that intermediate portion.

An angle between the first end portion and the intermediate portion may be between <NUM>° and <NUM>°. An angle between the second end portion and the intermediate portion may be between <NUM>° and <NUM>°. These angles may be the same. The angle(s) may be approximately <NUM>°.

Each of the plurality of foreline segments may have a diameter selected from the range of diameters consisting of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

The kit of parts may further comprise one or more elements selected from the groups of elements consisting of: one or more traps configured to be attached to a respective foreline segment; one or more reactors configured to be mounted within a respective foreline segment; one or more bellows configured to be attached to an end of a respective foreline segment; and one or more filters configured to be coupled to a respective foreline segment.

For each foreline segment, a distal end of the first end portion may comprise a first flange. For each foreline segment, a distal end of the second end portion may comprise a second flange.

In a further aspect, there is provided a foreline comprising the coupled together plurality of foreline segments of the kit of parts of any preceding aspect.

The foreline may comprise exactly two foreline segments and exactly three substantially straight further foreline segments. The foreline segments and the further foreline segments may be alternatingly attached together.

In a further aspect, there is provided a system comprising a process chamber, a vacuum pumping and/or abatement system, and a foreline attached between the process chamber and the vacuum pumping and/or abatement system. The foreline is in accordance with any preceding aspect.

<FIG> is a schematic illustration (not to scale) showing a semiconductor fabrication plant <NUM>, according to an embodiment.

The semiconductor fabrication plant <NUM> comprises a cleanroom <NUM> and a so-called subfab <NUM>. The cleanroom <NUM> and the subfab <NUM> are separated by a structure <NUM> that forms a floor of the cleanroom <NUM> and a ceiling of the subfab <NUM>.

The cleanroom <NUM> is a room in which semiconductor fabrication takes place. The air in the cleanroom <NUM> is maintained at typical clean room purity levels by an appropriate gas/air filtration and distribution system (not shown).

The cleanroom <NUM> comprises plurality of process chambers <NUM>.

Each of the process chambers <NUM> is configured to receive a process gas from a process gas source (not shown) and, using the received process gas, perform an etch process to chemically remove layers from surfaces of wafers located within the process chamber <NUM>.

The subfab <NUM> is located directly below the cleanroom <NUM>. The subfab <NUM> may be a room in which is maintained an air cleanliness level greater than a predetermined threshold.

The subfab <NUM> comprises plurality of gas pumping stations <NUM>.

In this embodiment, the gas pumping stations <NUM> comprise one or more vacuum pumps, and may additionally include abatement apparatus. Each gas pumping station <NUM> is coupled to a respective one of the process chambers <NUM> by means of a respective foreline, or suction line, <NUM>.

Each foreline <NUM> extends between a respective gas pumping station <NUM> and process chamber <NUM> pair. Each foreline <NUM> passes through a respective opening <NUM> in the structure <NUM>.

Each gas pumping station <NUM> is configured to evacuate and maintain controlled gas flows in the process chamber <NUM> coupled thereto. Each gas pumping station <NUM> is configured to pump, via its respective foreline <NUM>, exhaust gases out the process chamber <NUM> coupled thereto. Each gas pumping station <NUM> may be further configured to dispose of said pumped exhaust gases.

In this embodiment, each foreline <NUM> is a modular foreline formed of a plurality of modules or modular components. In other words, each foreline <NUM> is formed from a kit of parts. In particular, in this embodiment, each foreline <NUM> comprises a plurality of foreline segments, namely a first foreline segment <NUM>, a second foreline segment <NUM>, a third foreline segment <NUM>, a fourth foreline segment <NUM>, and a fifth foreline segment <NUM>.

Each of the foreline segments <NUM>-<NUM> comprises a respective pair of flanges, one at either end of that foreline segment <NUM>-<NUM>. In particular, the first foreline segment <NUM> comprises a first flange <NUM> at its first end and a second flange <NUM> at its second end. The second foreline <NUM> segment comprises a first flange <NUM> at its first end and a second flange <NUM> at its second end. The third foreline <NUM> segment comprises a first flange <NUM> at its first end and a second flange <NUM> at its second end. The fourth foreline <NUM> segment comprises a first flange <NUM> at its first end and a second flange <NUM> at its second end. The fifth foreline <NUM> segment comprises a first flange <NUM> at its first end and a second flange <NUM> at its second end.

Each of the flanges surrounds a respective opening of the foreline segment.

The foreline segments <NUM>-<NUM> are connected together as follows. The first flange <NUM> at the first end of the first foreline segment <NUM> is connected to a respective process chamber <NUM>. The second flange <NUM> at the second end of the first foreline segment <NUM> is connected to the first flange <NUM> at the first end of the second foreline segment <NUM>. The second flange <NUM> at the second end of the second foreline segment <NUM> is connected to a first flange <NUM> at the first end of the third foreline segment <NUM>. The second flange <NUM> at the second end of the third foreline segment <NUM> is connected to the first flange <NUM> at the first end of the fourth foreline segment <NUM>. The second flange <NUM> at the second end of the fourth foreline segment <NUM> is connected to the first flange <NUM> at the first end of the fifth foreline segment <NUM>. The second flange <NUM> at the second end of the fifth foreline segment <NUM> is connected to a respective gas pumping station <NUM>. Connections between the connected together flanges may be provided, e.g. by bolts passing through those flanges.

The flanges <NUM>-<NUM> may be configured to provide vacuum compatible sealing between connected together foreline segments. The flanges <NUM>-<NUM> may be compatible with any appropriate standard, such as the ISO standard for flanges.

In this embodiment, the foreline segments <NUM>-<NUM> are configured such that the flanges <NUM>-<NUM> are substantially horizontal.

Each of the foreline segments <NUM>-<NUM> may be considered to be a pipe having a substantially circular cross section. The diameters of the foreline segments <NUM>-<NUM> may be substantially the same. The diameter of each foreline segment <NUM>-<NUM> may be between about <NUM> and <NUM>. For example, the diameter may be a standard ISO diameter of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>.

In this embodiment, the first, third, and fifth foreline segments <NUM>, <NUM>, <NUM> are substantially straight foreline segments, i.e. substantially straight pipes. The first, third, and fifth foreline segments <NUM>, <NUM>, <NUM> are arranged vertically.

The length of each of the first, third, and fifth foreline segments <NUM>, <NUM>, <NUM> is preferably greater than or equal to ten times its diameter. For example, a straight foreline segment having a diameter of about <NUM> may have a length of at least <NUM>.

In this embodiment, the second and fourth foreline segments <NUM>, <NUM> may be identical to one another. The second and fourth foreline segments <NUM>, <NUM> are non-straight, i.e. bent foreline segments.

In particular, in this embodiment each of the second and fourth foreline segments <NUM>, <NUM> comprises a first substantially straight end portion 122a, 124a, a second substantially straight end portion 122b, 124b opposite to the first end portion 122a, 124a, and an intermediate portion 122c, 124c disposed between the first end portion 122a, 124a and the second end portion 122b, 124b. The intermediate portion 122c, 124c is connected to the first end portion 122a, 124a by a first bend 122d, 124d. The intermediate portion 122c, 124c is connected to the second end portion 122b, 124b by a second bend 122e, 124e. The first end portion 122a, 124a and the second end portion 122b are substantially parallel to each other. The intermediate portion 122c, 124c is oblique to the first end portion 122a, 124a and the second end portion 122b, 124b.

The second and fourth foreline segments <NUM>, <NUM> are positioned such that the first end portions 122a, 124a and the second end portions 122b, 124b are arranged vertically.

In this embodiment, the angles <NUM> between the end portions 122a, 124a, 122b, 124b and the intermediate portions 122c, 124c disposed therebetween may be an angle between about <NUM>° and <NUM>°. For example, the angle <NUM> any be about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, about <NUM>°, or about <NUM>°. More preferably, the angle <NUM> is <NUM>°. In some embodiments, the angle <NUM> is between about <NUM>° and <NUM>°. In some embodiments, the angle <NUM> is between about <NUM>° and <NUM>°.

The length of each intermediate portion 122c, 124c is preferably greater than or equal to ten times its diameter. For example, for a straight intermediate portion having a diameter of about <NUM> may have a length of at least <NUM>.

For the multiple forelines <NUM>, the first foreline segments <NUM> of the forelines <NUM> may be substantially identical to one another. The second foreline segments <NUM> of the forelines <NUM> may be substantially identical to one another. The third foreline segments <NUM> of the forelines <NUM> may be substantially identical to one another. The fourth foreline segments <NUM> of the forelines <NUM> may be substantially identical to one another. The fifth foreline segments <NUM> of the forelines <NUM> may be substantially identical to one another.

In some embodiments, the first foreline segments <NUM> are substantially identical to the third foreline segments <NUM>. In some embodiments, the first foreline segments <NUM> are substantially identical to the fifth foreline segments <NUM>. In some embodiments, the second foreline segments <NUM> are substantially identical to the fourth foreline segments <NUM>.

In this embodiment, each of the foreline segments <NUM>-<NUM> has a respective vertical length, or height. In particular, the first foreline segment <NUM> has a first vertical length <NUM>, the second foreline segment <NUM> has a second vertical length <NUM>, the third foreline segment <NUM> has a third vertical length <NUM>, the fourth foreline segment <NUM> has a fourth vertical length <NUM>, and the fifth foreline segment <NUM> has a fifth vertical length <NUM>.

Preferably, the vertical lengths <NUM>-<NUM> of the foreline segments <NUM>-<NUM> are all equal to a respective integer multiple of a common value D, where D may take any appropriate value. The value D may be, for example, a value in the range <NUM> - <NUM>, or more preferably <NUM> - <NUM>, or more preferably <NUM> - <NUM>, or more preferably <NUM> - <NUM>, or more preferably <NUM> - <NUM>, or more preferably <NUM> - <NUM>, or more preferably <NUM> - <NUM>, or more preferably <NUM> - <NUM>, or more preferably <NUM> - <NUM>. Example x values include, but are not limited to, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. Preferably, D is equal to <NUM> or about <NUM>. The exact value chosen for D tends not to be critical and any appropriate value can be chosen.

In some embodiments, the vertical lengths <NUM>-<NUM> of the foreline segments <NUM>-<NUM> are all equal, e.g. equal to x. Thus, the vertical height of a foreline <NUM> is 5x. The height x may be any appropriate value, e.g. <NUM>.

In some embodiments, the vertical lengths <NUM>-<NUM> of the foreline segments <NUM>-<NUM> are not all equal. For example, the first, third, and fifth segments <NUM>, <NUM>, <NUM> may have a vertical height of x, while the second and fourth segments <NUM>, <NUM> may have a vertical height of y, where y is not equal to x. The vertical height of a foreline <NUM> is then 3x + 2y. The height x may be any appropriate value. The height y may be any appropriate value.

In this embodiment, each foreline <NUM> is may be considered to be a modular pipe or conduit comprising alternating straight sections and non-straight sections, which are detachably attached together. There are three straight sections and two non-straight sections in each foreline <NUM>.

Each foreline <NUM> is a pipe comprising a plurality of bends. Preferably, the bends are swept bends having angles such as those described above, as opposed to sharp bends.

<FIG> is a schematic illustration (not to scale) showing an alternative modular foreline connecting a process chamber and a vacuum pumping system. In <FIG>, elements that are the same as those shown in <FIG> and described in more detail earlier above are indicated using the same reference numerals as those of <FIG>, and will not be described again for the sake of brevity.

In this embodiment, the modular foreline <NUM> further comprises a plurality of traps <NUM> and a plurality of in-line reactors <NUM>. Thus, the kit of parts from which a foreline <NUM> is constructed additionally comprises, in this embodiment, a plurality of traps 200a,b and a plurality of reactors <NUM>.

The traps 200a,b may be devices that capture gases and vapours from the exhaust gas being pumped through the foreline <NUM>. The traps 200a,b may be any appropriate type of traps, including but not limited to ambient alumna traps.

The traps 200a,b are modular elements which are attachable and detachable from the foreline sections <NUM>-<NUM>. The traps 200a,b may be configured to attach to the foreline sections at any appropriate position.

In this embodiment, a first trap 200a is connected to the second foreline segment <NUM>. In particular, in this embodiment, the second foreline segment <NUM> further comprises a further opening surrounded by a third flange <NUM> (not present in the embodiment shown in <FIG>). The third flange <NUM> is located at the first bend 122d of the second foreline segment <NUM>, opposite to and vertically below the first flange <NUM>. The first trap 200a comprises a flange 201a which is connected to, e.g. by bolts, third flange <NUM>.

Similarly, in this embodiment, a second trap 200b is connected to the fourth foreline segment <NUM>. In particular, in this embodiment, the fourth foreline segment <NUM> further comprises a further opening surrounded by a third flange <NUM> (not present in the embodiment shown in <FIG>). The third flange <NUM> is located at the first bend 124d of the fourth foreline segment <NUM>, opposite to and vertically below the first flange <NUM>. The second trap 200b comprises a flange 201b which is connected to, e.g. by bolts, third flange <NUM>.

The traps 200a,b may include valves, e.g. for maintenance.

The reactors <NUM> may be any appropriate type of reactors for treating an exhaust gas in the foreline, for example foreline plasma reactors.

The reactors <NUM> are modular elements which are attachable and detachable from the foreline sections <NUM>-<NUM>. The reactors <NUM> may be mountable within the foreline sections <NUM>-<NUM>. In this embodiment, the reactors <NUM> are positioned within straight portions of foreline sections, specifically within the third and fifth foreline sections <NUM>, <NUM>.

Thus, a modular system for constructing a foreline of a vacuum pumping system is provided.

Advantageously, the modules (i.e. the foreline subsections, and ancillary devices) can be easily and efficiently arranged and attached together to provide multiple different system configurations. Multiple different example configurations are shown in <FIG>. This advantageously allows a degree of flexibility and control in the positioning of the gas pumping systems with respect to one another, and with respect to the process chambers. For example, using the above-described system it tends to be possible to space apart the gas pumping systems to a greater extent than compared to, say, using straight forelines. This tends to make maintenance and repair of the gas pumping systems easier.

The modules can be manufactured and prepared in advance of the system being designed and installed, thereby reducing cost and lead time.

The space (or footprint) occupied by an installed vacuum pumping and/or abatement system tends to be an important factor in system design. A reduced footprint tends to lead to decreased costs and/or greater productivity. Advantageously, with the above-described modular system, greater control of the footprint of the installed system tends to be provided.

The above-described modular system tends to speed-up manufacture and installation of forelines in semiconductor fabrication plants. The modular system is a kit of parts comprising a plurality of pipes, each pipe having a standard length and diameter. The kit may allow for multiple forelines to be constructed, each of the forelines having a different shape or configuration, while still having the same number of bends and straight sections as the other forelines. Thus, the differently configured/differently shaped forelines tend to provide substantially the same vacuum performance as each other. This tends to facilitate chamber matching, i.e. the matching of performance between multiple different process chambers.

Conventionally, having highly variable bespoke forelines tend to make installing Temperature Management Systems (TMS) difficult. Also, consistent quality control of bespoke forelines tends to be difficult to guarantee. The above-described modular foreline system tends to address these problems.

The above-described modular foreline system tends to provide consistent geometry and conductance to each process chamber, support variation in fab/subfab layout, incorporate standardized interfaces and size (diameter and length) increments, facilitate the inclusion of integrated TMS with measurement, allow for the inclusion of foreline traps/deadlegs, facilitate foreline cleaning, repair, and maintenance, and support fitment of instrumentation and leak testing.

In the above embodiments, the modular foreline system, i.e. the kit of parts, comprises a plurality of straight segments (e.g. the first, third, and fifth segments) and a plurality of segments comprising multiple bends (e.g. the second and fourth segments). However, in other embodiments, the kit comprises different parts. In some embodiment, the straight segments may be omitted. In some embodiments, differently shaped segments may be included, for example segments having only a single bend may be included.

In the above embodiments, each foreline comprises exactly three straight segments and exactly two segments comprising multiple bends, which are alternatingly attached together. However, in other embodiments, each foreline comprises a different number of straight segments (e.g. none, less than three, more than <NUM>) and/or a different number of segments comprising multiple bends (e.g. one, more than two). The segments that make up the foreline may be attached together in a different configuration, e.g. not the alternating arrangement shown in <FIG> and <FIG>.

In embodiments, one or more or, and more preferably all of, the foreline segments of the modular system are heated, i.e. include respective heating means for heating a gas flowing through that segment. Examples of heating means include, but are not limited to, jackets that may be wrapped around a pipe segment and controlled so as to heat that pipe segment. Preferably, the respective heating means are independently controllable from one another. Thus, an assembled foreline comprises multiple independently controllable heating zones along its length.

Claim 1:
A kit of parts for forming a foreline (<NUM>) for coupling a process chamber (<NUM>) to a vacuum pumping and/or abatement system, the kit comprising:
a plurality of foreline segments (<NUM>, <NUM>); wherein
each foreline segment (<NUM>, <NUM>) is a pipe that comprises:
a first straight end portion (122a, 124a);
a second straight end portion (122b, 124b) opposite to the first end portion (122a, 124a); and
an intermediate portion (122c, 124c) disposed between the first and second end portions (122a, 122b, 124a, 124b) and connected to the first and second end portions (122c, 124c) by respective bends (122d, 122e, 124d, 124e);
the first and second end portions (122a, 122b, 124a, 124b) are parallel to each other;
the intermediate portion (122c, 124c) is oblique to the first and second end portions (122a, 122b, 124a, 124b); and
the foreline segments (<NUM>, <NUM>) in the plurality of foreline segments (<NUM>, <NUM>) are configured to be attached together so as to form a continuous foreline (<NUM>);
characterised in that
one or more of the foreline segments (<NUM>, <NUM>) comprises a means for heating a gas flowing through that segment (<NUM>, <NUM>).