Patent Application
20190385874
Embodiments of the present principles generally relate to semiconductor process chambers.
Many semiconductor processes require the flow of gases through a process chamber during processing. The gas flow may be part of the process such as the flow of oxygen to enhance oxidizing steps or may be part of setting up a process such as evacuating a chamber or conditioning a chamber. Flowing gases can be used for deposition of materials such as in a lateral flow deposition chamber or for removing unwanted gases given off during degassing or to aid in removing moisture from substrates. Although the flow of gases may be a common denominator in the different processes, the parameters of the flowing gases vary greatly, even within a single type of process. The inventors have observed that the gas flow parameters are typically determined when the process chamber is designed and cannot be easily varied once the chamber is in operation.
Thus, the inventors have provided improved methods and apparatus for optimizing gas flow in a semiconductor process chamber.
Methods and apparatus for controlling gas flow in semiconductor process chambers.
In some embodiments, an apparatus for controlling gas flow in a process chamber comprises at least one gas flow plate insertable into a side wall of an internal volume of a process chamber, the least one gas flow plate having a plurality of through holes such that gas flowing through the plurality of through holes is directed into the internal volume of the process chamber.
In some embodiments, the apparatus further comprises wherein the at least one gas flow plate is opaque to microwaves, wherein at least one of the plurality of through holes has a diameter different from at least one other hole of the plurality of through holes, wherein at least one of the plurality of through holes has an orientation through the at least one gas flow plate different from at least one other hole of the plurality of through holes, wherein at least one of the plurality of through holes has a diameter of approximately four millimeters, wherein the at least one gas flow plate has a flat or curved gas outlet surface, wherein at least one of the plurality of through holes has a diameter of between greater than zero and approximately five millimeters, wherein the at least one gas flow plate is configured to flow gas at a rate of approximately 1,000 standard cubic centimeter per minute (sccm) to approximately 25,000 sccm, a gas flow control assembly removable from the process chamber, wherein the gas flow control assembly forms a portion of a side wall of the internal volume and provides at least one mounting location for the at least one gas flow plate, and/or wherein the gas flow control assembly has at least one gas flow cavity fluidly coupled and adjacent to the at least one mounting locating for the at least one gas flow plate.
In some embodiments, an apparatus for processing semiconductors comprises a process chamber with an internal volume for processing and at least one gas flow plate removable from a wall of the internal volume of the process chamber, the gas flow plate having a plurality of through holes such that gas flowing through the plurality of through holes is directed into the internal volume of the process chamber from at least one gas flow cavity.
In some embodiments, the apparatus further comprises wherein the process chamber is a degas chamber, a microwave chamber, or a lateral flow deposition chamber; wherein the process chamber is configured to process a plurality of substrates in a stacked formation; wherein the plurality of through holes of the at least one gas flow plate form at least one row of through holes that align with at least one space between substrates when present in the process chamber; and/or wherein the at least one gas flow plate including a first gas flow plate with a first plurality of through holes configured to flow a first gas and a second gas flow plate with a second plurality of through holes configured to flow a second gas.
In some embodiments, a method of controlling gas flow in a process chamber comprises selecting a first set of at least one gas flow plate such that a gas flow pattern for a process in an internal volume of the process chamber is achieved and removably inserting the first set of at least one gas flow plate into the process chamber such that a gas flow into an internal volume of the process chamber is controlled at least partially by the first set of at least one gas flow plate.
In some embodiments, the method further comprises selecting the first set of at least one gas flow plate based at least partially on a number of through holes, at least one through hole diameter, orientation of at least one through hole, or a position of at least one through hole relative to spacing between substrates to aid in achieving the gas flow pattern; selecting the first set of at least one gas flow plate based at least partially on at least one processing parameter including a type of processing, dimensions of the internal volume of the processing chamber, a number of substrates to be processed in the processing chamber, spacing between stacked substrates to be processed in the processing chamber, gas flow pressure and gas flow rate for a gas to be used in the processing chamber, or materials of substrates to be processed in the processing chamber; and/or selecting a second set of at least one gas flow plate when at least one parameter changes and removably inserting the second set of at least one gas flow plate into the process chamber such that a gas flow into an internal volume of the process chamber is controlled at least partially by the second set of at least one gas flow plate.
Other and further embodiments are disclosed below.
Embodiments of the present principles, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the principles depicted in the appended drawings. However, the appended drawings illustrate only typical embodiments of the principles and are thus not to be considered limiting of scope, for the principles may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Gas flow is important for effective moisture removal during the processing of packaging wafers. The wafers are typically heated in batches, and the moisture is removed. If the moisture is not purged effectively, the wafers may re-absorb moisture resulting in a low yield for the moisture removal process. The flow rate, direction, and pressure of a gas may change for different batch sizes, wafer types, and heating patterns. The methods and apparatus of the present principles allow for an easily reconfigurable gas flow control system for different processing conditions and different process chambers. The high flexibility of the methods and apparatus advantageously provide optimal flow conditions in the same chamber for any given processing condition including, but not limited to, different pressure regimes and heating non-uniformities, preventing loss of quality of degas or yield. The inventors have found that multiple optima can exist for multiple process conditions, and the methods and apparatus beneficially allow for such conditions.
The methods and apparatus allow for the removal and re-configurability of the gas flow plate for processing substrates in a process chamber. Different gas flow plates with different patterns of flow through holes can be replaced easily in a process chamber for different process conditions. The methods and apparatus may be used with, but is not limited to, curing, degas, and lateral flow deposition chambers, and the like. In some embodiments, an optimal condition may be obtained for thermal and degas uniformities when conditions for process, wafer types, or wafer positions change. The methods and apparatus also advantageously allow testing of different conditions and scenarios based on, but not limited to, wafer types, positions, and operating pressures. The high flexibility of gas flow control is especially beneficial for microwave degas chambers where heating uniformity is very sensitive to different process conditions, and gas flow has to be adjusted accordingly.
The methods and apparatus provide one or more removable gas flow plates with a plurality of through holes to control gas flow into an internal volume of a process chamber. In some embodiments, the through holes may differ from gas flow plate to gas flow plate in diameter, number, diameter spread within the holes, and the angles of the holes (orientation). During a process, the operating pressure, ramp, and soak durations may be decided based on the required temperatures and wafer types. For example, an epoxy wafer may have a different heat up rate and soak temperature compared to that of a silicon wafer with a polyimide layer or a thinner wafer. The wafer positions may also need to be changed due to the heat distribution (e.g., in the case of microwave based processes) which also depends on wafer positions. In some embodiments, based on, but not limited to, the process selected, the through holes in the gas flow plates may be configured either numerically or experimentally by multiple iterations or with the use of multiple computational models. The end choice of the gas flow plates may be such as to obtain minimum residual moisture in the wafers, with a maximum uniformity of purge on each wafer.
In some embodiments, the spacing 612-616 between rows of the plurality of through holes 602 may be varied to align with the spacing between substrates in the internal volume 114 of the process chamber 102 or based on a determined flow pattern in the internal volume 114 of the process chamber 102 and the like. In some embodiments, the column spacing 622-632 of the plurality of through holes 602 may be varied based on the orientation of a particular through hole, size of a particular through hole, or a particular determined dispersion of the gas flow within the internal volume 114 and the like. In some embodiments, a row of the plurality of through holes 602 may be linear or non-linear (e.g., offset or randomly dispersed above or below a linear line). In some embodiments, a row of the plurality of through holes 602 may be of the first diameter with more than one orientation. In some embodiments, a row of the plurality of through holes 602 may be of the first diameter with the same orientation. In some embodiments, a row of the plurality of through holes may have a plurality of diameters and one or more orientations. Similarly, in some embodiments, a column of the plurality of through holes 602 may be linear or non-linear and may have one or more diameters with one or more orientations. In some embodiments, a row or column may not have evenly spaced through holes or a complete set of through holes for the column or row.
The through hole sizes or diameters may be varied based on a particular flow pattern for the internal volume 114 of the process chamber 102. The inventors have found that the diameters of the through holes may range from greater than zero to approximately five millimeters. The inventors have also found that an approximately four millimeter through hole size advantageously provides an enhanced flow pattern. The inventors have also found that advantageous flow rates may vary from approximately 1,000 standard cubic centimeter per minute (sccm) to approximately 25,000 sccm.
In block 704, the selected first set of at least one gas flow plate is removably inserted into the process chamber such that at least one gas flow into an internal volume of the process chamber is controlled at least partially by the first set of at least one gas flow plate. As discussed above, the gas flow plate may be inserted as part of a wall of the internal volume of the process chamber. In some embodiments, the gas flow plate may be removably inserted by using screws and the like. In some embodiments, the gas flow plate may be secured, at least partially, by an insertion tab or protrusion and the like that interacts with the wall of the internal volume. The gas flow plate is opaque to microwaves and will not interfere with processes such as drying or curing processes that employ microwaves.
In block 706, a second set of at least one gas flow plate is selected when at least one process parameter changes. In some embodiments, the second set of at least one gas flow plate may include at least a portion of the first set of at least one gas flow plate. The changed parameter may require additional flow rates, less flow rates, and/or different orientations of through holes in a gas flow plate and the like. In block 708, the second set of at least one gas flow plate is removably inserted into the process chamber. In some embodiments, the second set of at least one gas flow plate may include one or more gas flow plates of the first set of at least one gas flow plate.
In some embodiments, the gas flow plates may be interchanged based on uniformity and/or temperature control parameters that are adjusted to enhance a process. The first or second set of gas flow plates may be selected and removably inserted into the process chamber to effect better performance of a process rather than based on a process parameter change. The inventors have found that the configurability and the removability of the gas flow plates greatly enhances the flexibility afforded to an operator of a process chamber to maximize both performance and productivity of a process chamber.
While the foregoing is directed to embodiments of the present principles, other and further embodiments of the principles may be devised without departing from the basic scope thereof.
