US PATENT SUBCLASS 117 / 13
.~ Having pulling during growth (e.g., Czochralski method, zone drawing)

Current as of: June, 1999
Click HD for Main Headings
Click for All Classes

Internet Version by PATENTEC © 1999      Terms of Use


117 /   HD   SINGLE-CRYSTAL, ORIENTED-CRYSTAL, AND EPITAXY GROWTH PROCESSES; NON-COATING APPARATUS THEREFOR

11  DF  PROCESSES OF GROWTH FROM LIQUID OR SUPERCRITICAL STATE {7}
13.~ Having pulling during growth (e.g., Czochralski method, zone drawing) {9}
14  DF  .~.~> With a step of measuring, testing, or sensing (e.g., using TV, photo, or X-ray detector or weight changes) {1}
17  DF  .~.~> With contact with an immiscible liquid (e.g., LEC) {1}
19  DF  .~.~> Forming an intended mixture (excluding mixed crystal) (e.g., doped) {2}
23  DF  .~.~> Shape defined by a solid member other than seed or product (e.g., edge-defined film-fed growth, Stepanov method) {3}
28  DF  .~.~> Including non-coincident axes of rotation (e.g., relative eccentric)
29  DF  .~.~> Passing non-induced electric current through a crystal-liquid interface (e.g., Peltier)
30  DF  .~.~> With liquid flow control or manipulation during growth (e.g., mixing, replenishing, magnetic levitation, stabilization, convection control, baffle) {3}
35  DF  .~.~> With a significant technique for (a) preliminary preparation or growth starting or (b) product handling or growth ending (e.g., arrangement of or crystallography of seed)
36  DF  .~.~> Precursor intentionally contains an excess component or a non-product appearing component (e.g., solvent, flux, crystal lattice modifier)

DEFINITION

Classification: 117/13

Having pulling during growth (e.g., Czochralski method, zone drawing):

(under subclass 11) Subject matter characterized by bringing a seed* into contact with a liquid precursor* (or nutrient*) media to initiate and conduct the growth process by then withdrawing it under conditions which permit crystal formation while pulling.

(1) Note. The salient feature of this and indented subclasses is the necessary and sufficient requirement of relative movement between the crystal product (holder) and the nutrient* supply holder (or means).

(2) Note. Processes termed zone drawing or zone pulling in which a zone of melted material is moved through a solid precursor* while simultaneously conducting a drawing or pulling operation and wherein the drawing or pulling causes the product to have a cross-sectional mass different from the solid precursor* are properly placed in this subclass and its indents. This subclass also includes those processes in which a product has a larger diameter than the precursor*. These might be termed "pushing" techniques as opposed to pulling

techniques. For example see U.S. Patent No. 3,622,282.

(3) Note. Although a crucible* with a reservoir of nutrient* is typical of these processes, this is not a requirement.

(4) Note. This subclass and its indents do not include processes in which crystal pulling is used only to initiate the crystallization. For example, pulling initially and then switching to moving zone process is proper for subclasses 37+.

(5) Note. The moving zone, Bridgman-Stockbarger, and crystal pulling methods each involve a moving solid-liquid interface with a trailing recrystallization. The following typical indicia are provided to help in distinguishing them from each other.

(a) Moving zone recrystallization:

Two solid-liquid interfaces are present and are generally planar and generally parallel to each other.

Both precursor* and product are attached to and moved by the same means or are controlled so as to move so that there is no relative movement between them, or both precursor* and product are attached to the same structure and the heating means is moved, but again there is no relative movement between precursor* and product.

The precursor* may be a layer (e.g., a coating) or may be sandwiched between two layers.

In the case of crucibleless zone melting, there is no disparate-material crucible*.

Precursor* and product travel along a common axis and travel at the same rate, or the heating element moves while the precursor* and product remain stationary.

The heating element may be immersed in the liquid zone.

(b)

Bridgman-Stockbarger method:

There is one solid-liquid interface.

The crystal grows into the nutrient*.

There is a vessel which contains the liquified precursor* and the crystal product. (c)

Crystal pulling:

A seed* material is moved into contact with the precursor*, and then withdrawn so as to pull the precursor* from the liquid by surface tension into a cooler zone where single-crystallization* occurs.

There may be no replenishment of precursor* during the process, in which case there will be only one solid-liquid interface; e.g., the precursor* is completely liquefied and contained in a crucible*.

There may be another solid-liquid interface associated with liquefying of solid precursor* replenishment.

Direction of travel of the precursor* material (or precursor* replenishment material) and the product are unrelated to each other.

The seed* is attached to a pulling means/structure.

The crucible* may be composed of precursor* material and thus may be consumed.

(6) Note. The pulling of a body which results in a polycrystalline rod will generally be found in Class 23 if no chemical reaction occurs and Class 423 if a chemical reaction occurs. If shaping means are employed (e.g., EDFFG*), the polycrystallization process will generally be found in Class 264.

SEE OR SEARCH THIS CLASS, SUBCLASS:

12, for processes of growing wherein there is movement of discrete droplets or solid particles (e.g., Verneuil method). 37+, for processes of moving zone recrystallization without a pulling or drawing operation.

54+, for processes of immersing a substrate* or seed* and then withdrawing it, either to cause epitaxy* or after epitaxy* has occurred.

208+, for corresponding apparatus other than coating apparatus.