Combinatorial synthesis system

Details Combinatorial synthesis system Combinatorial synthesis system

2000-03-14

2002-12-10

Mills, Gregory (Department: 1763)

Coating apparatus

Gas or vapor deposition

With treating means

C118S7230VE, C118S7230CB, C118S7230EB

Reexamination Certificate

active

06491759

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the field of materials research, and more in particular, to simultaneous creation of numerous diverse compounds in one step for further analysis, testing, and evaluating of different properties of these compounds as the entire multi-component system created on a single substrate.
The present invention further relates to a combinatorial synthesis technique which is based on pulsed laser deposition or other deposition techniques based on ablation due to an energetic beam such as a pulsed electron beam, in combination with a continuous composition spread technique resulting in a deposition film formed on a substrate having a continuously varying composition of a plurality of selected ingredient materials.
Further, the present invention relates to a combinatorial synthesis system and method in which a plurality of targets are ablated in a predetermined sequence by an energetic beam, such as a laser beam or a pulsed electron beam, such that the ejected materials reach a substrate at predefined locations thereon and form a plurality of deposition centers on the substrate. Each deposition center is surrounded by a distributed deposition area with a lower concentration of the material than at the corresponding deposition center. The distributed deposition areas of all deposition centers overlap each other forming a deposition film on the surface of the substrate having a continuously varying composition of the ingredient materials of the targets.
The present invention still further relates to a combinatorial synthesis system in which each target during the time of exposure to energetic pulses, such as laser pulses, is aligned with a corresponding deposition center on the substrate by means of a control mechanism which controls a mutual disposition between the energetic beam, targets, and the substrate in the following manner:
A. Either the energetic beam is maintained immovable, and the targets are displaced (rotated on the target carousel) to bring a target into operational engagement with the energetic beam, additionally, the substrate is rotated to align the predefined deposition center with a corresponding target; or
B. The substrate and/or the targets are maintained stationary and the energetic beam is steered from target to target which may or may not be repositioned during the deposition. The energetic beam also may be controlled to scan over the surface of a particular target to further control the composition deposited on the substrate.
A deposition film created in this manner on the surface of the substrate having a continuously varying composition of the ingredient materials may then be further analyzed, tested, and evaluated in searching for a compound having specific physical, electrical, optical, etc., properties.
BACKGROUND OF THE INVENTION
Combinatorial chemistry was introduced in the mid 1980s as a method by which drug researchers could quickly make and evaluate a large number of products and check the biological activity. Combinatorial chemistry has attracted intense interest in the scientific community. Combinatorial chemistry is an approach in which a large number of compounds are synthesized without thorough predictions of likely reactions or the properties of the resulting substances. In its basic parallel synthesis form, combinatorial chemistry uses an array of tiny wells in a plastic sheet filled row by row with chemicals A
1
, A
2
, A
3
. . . , and column by column with reacting chemicals B
1
, B
2
, B
3
. . . Each well's reaction product is analyzed with a generalized test of biological activity and those giving positive results are pursued.
More recently, the combinatorial approach has been applied to thin film materials synthesis with the expectations of developing new luminescent materials, magnetoresistive compounds, dielectric and ferroelectric materials, catalysts, polymers, and high-T
c
superconductors. In this approach, an array of thin film squares are deposited on a single substrate, each with a slightly different composition. Presently, researchers are applying combinatorial chemistry techniques to optical, electronic, superconductive and magnetic materials for differences in bulk compositions, layer compositions, layer thicknesses, composition changes with respect to depth, and magnetic properties. Present day material science examines the small compositional differences that may induce profound property changes.
There are several techniques in the combinatorial chemistry used to create a plurality of different compounds on a single substrate for further analysis, testing and evaluation. In the discrete combinatorial synthesis (DCS) approach, a series of masks is used to deposit separate layers of the ingredient materials. As shown in
FIGS. 1A-1D
, different materials A, B, C, and D are deposited in sequence through masks (not shown) followed by a high temperature anneal to promote reaction of the components. This forms different compounds of the ingredient materials, as shown in FIG.
1
E. Large numbers of materials may be synthesized in a single run. The masks have to be brought in close contact with the substrate in order to permit the required spatial resolution. In many situations this requires the deposition to take place at room temperature since handling of complex delicate masks at elevated temperatures poses a difficulty.
More fundamentally, discrete combinatorial synthesis techniques require a high temperature anneal after deposition of the precursor layers in order to promote intermixing of the components and is thus not suitable for the exploration of low temperature processed materials.
A high temperature DCS system has been developed by Pascal Corporation, Ltd. (Japan). Disadvantageously, this system allows a very limited number of compositions to be generated per run at a relatively high cost. Clearly, the elevated cost of such systems in combination with the limited number of compositions generated per run prohibit commercial widespread use.
Another discrete combinatorial synthesis system is described in U.S. Pat. No. 5,985,356 in which a substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate. Simultaneously the components are reacted to form at least two materials. In this system, eight RF magnetron sputtering guns each of which contains a reactant component of interest are located above a disk containing eight masking patterns as well as eight film thickness monitors.
The magnetron sputtering guns, as well as the disk, are fixed in this system. The substrate is coupled to a substrate manipulator which is capable of linear and rotational motion and which engages the substrate with a particular mask of interest so that the substrate is in contact with the mask when the sputtering is initiated. Combinations of the eight components are generated on the substrate by the sequential deposition of each component through its respective mask.
To overcome deficiencies of the described combinatorial synthesis techniques, the continuous composition spread (CCS) technique has been introduced in 1970 by J. T. Hanak. In this type of proposed system films are deposited by co-sputtering from a disk-shaped target consisting of 120° sectors of three different materials. In 1998, R. B. Van Dover, et al. introduced a CCS technique by reactive co-sputtering using planar magnetron sputter guns arranged at 90° intervals around a rectangular substrate. Zr, Ti and Sn guns are typically run at 150 watt, 75 watt, and 20 watt of radio frequency power, respectively, in order to provide the desired Zr/Ti/Sn composition at the substrate midpoint. The deposited film constitutes a single film with a ternary composition spread, the critical properties of which are evaluated as a function of position.
The composition was inferred as a function of position using Rutherford backscattering spectroscopy together with independent calibration runs allowing a mapping of the “useful figure of merit” (FOM) data on

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