Browse Prior Art Database

Improved Chlorination of Diethyl Pyromellitate

IP.com Disclosure Number: IPCOM000037266D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Arnold, AF: AUTHOR [+4]

Abstract

An improved method of chlorinating diethyl pyromellitate, a component used in the manufacture of polyamic acid ethyl ester (PAETE), has been developed which results in a high purity final product. The PAETE is used as a planarizing insulator layer in the manufacture of semiconductor devices and its quality is critical to the performance of the finished device. (Image Omitted)

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Improved Chlorination of Diethyl Pyromellitate

An improved method of chlorinating diethyl pyromellitate, a component used in the manufacture of polyamic acid ethyl ester (PAETE), has been developed which results in a high purity final product. The PAETE is used as a planarizing insulator layer in the manufacture of semiconductor devices and its quality is critical to the performance of the finished device.

(Image Omitted)

In synthesizing PAETE, as shown in the figure, pyromellitic dianhydride (PMDA) (I) is esterfied by treatment with absolute ethyl alcohol (Step 1). This product is an isomer mix of roughly equal amounts of para- (II) and meta- (III) PMDA-di(ethyl)ester diacid (PMDA-DDA). These isomers are chlorinated in Step 2 into the corresponding diacyl chloride compound, PMDA-di(ethyl) diacyl chloride (PMDA-DDC). The isomerization of II and III is thus preserved as IV and V in PMDA-DDC. In Step 3, the isomers react with oxydianiline (ODA) in the presence of n-methyl morpholine to form a solution of PAETE polymer in n- methyl pyrrolidinone (NMP). The PAETE is subsequently separated and then used in a new, final solution.

The purity of the IV + V mixture is a critical factor since it affects the possible molecular weight of the polymer and the viscosity stability of the final solution. The chlorination process (Step 2) is subject to many variations resulting in unreacted starting material and byproducts which can cause premature chain termination and undesired...