Background Statement for SEMI Draft Document 4701B New Standard: GUIDE FOR HAFNIUM AMIDES

Transcription

1 Background Statement for SEMI Draft Document 4701B New Standard: GUIDE FOR HAFNIUM AMIDES Note: This background statement is not part of the balloted item. It is provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this document. Note: Recipients of this document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, patented technology is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided. 1 Introduction: As the semi-conductor industry continues in its efforts to follow Moore s Law many new materials have been introduced and continue to be introduced into electronic devices. The introduction of new materials being used covers all areas of the integrated circuit, including, but not limited to, high-k dielectric layers, barrier layers, metal interconnects, electrical contacts and low-k dielectric layers. Many of these new materials are deposited from liquid or solid chemicals by means of chemical vapour deposition or increasingly by atomic layer deposition. Therefore, there are now chemicals currently being used or could potentially be used in the future for which there are no SEMI guides or standards. The Precursor Specification Task Force held its first meeting at SEMICON Europa in 2004 to identify new chemicals currently being used and to draft guides for these chemicals. 2 Steps taken: With input from ITRS representatives The Precursor Specification Task Force initially examined which chemicals are currently being used or could potentially be used in the future for which there are no SEMI guides. The task force also examined the properties of these chemicals that are important for the deposition process and whether these could be included in a guideline. The Precursor Specification Task Force then selected a couple of chemicals to focus on initially with the aim of producing guides. In the case of hafnium several different precursors can be used for the atomic layer deposition of hafnium oxide based materials. Three of these precursors come from a single class of chemicals, namely amides. Therefore, it was decided to cover all three precursors using a single document rather than produce three virtually identical documents. An initial draft of the guide was produced based on task force discussions; this was then revised following comments from chemical manufactures, tool manufactures and end users. 3 Ballot Adjudication Information: This ballot and all responses to it will be adjudicated at the next meeting of the Europe Gases and Liquid Chemicals Committee, scheduled to be held at Intersolar 2010, 9-11 June 2010, Munich, Germany. i

2 SEMI Draft Document 4701B New Standard: GUIDE FOR HAFNIUM AMIDES 1 Purpose 1.1 The purpose of this document is to provide a guide for hafnium amides for which a need has been identified. 2 Scope 2.1 The scope of this document covers high purity hafnium amides, namely, tetrakis(dimethylamino) hafnium, tetrakis(diethylamino) hafnium and tetrakis(ethylmethylamino) hafnium which are used in the semiconductor industry for the deposition of hafnium oxide based layers by atomic layer deposition. 3 Limitations NOTICE: This standard does not purport to address safety issues, if any, associated with its use. It is the responsibility of the users of this standard to establish appropriate safety and health practices and determine the applicability of regulatory or other limitations prior to use. 4 Referenced Standards 4.1 SEMI Standards SEMI C1 Guide for the Analysis of Liquid Chemical. 4.2 ASTM Standards 1 ASTM D5127 Standard Guide for Ultra Pure Water Used in the Electronics and Semiconductor Industry NOTE 1: As listed or revised, all documents cited shall be the latest publications of adopted standards. 5 Terminology 5.1 Acronyms TDMAH - tetrakis(dimethylamino) hafnium TDEAH - tetrakis(diethylamino) hafnium TEMAH - tetrakis(ethylmethylamino) hafnium NMR nuclear magnetic resonance TMS tetramethylsilane 6 Physical Properties Table 1 Physical Properties of TDMAH and CAS number Molecular formulae Hf[N(CH 3 ) 2 ] g/mol CAS number C at 0.01mmHg Melting point log 10 P = /T C Colourless solid 1 American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, Pennsylvania , USA. Telephone: , Fax: Website: Page 1

3 Table 2 Physical Properties of TDEAH and CAS number Molecular formulae Hf[N(CH 2 CH 3 ) 2 ] g/mol CAS number C at 0.01mmHg log 10 P = /T Melting point Liquid at 25 C Liquid density at 25 C g/cm 3 Yellow/orange liquid Table 3 Physical Properties of TEMAH and CAS number Molecular formulae Hf[N(CH 2 CH 3 )(CH 3 )] g/mol CAS number C at 0.1mmHg log 10 P = /T Melting point Liquid at 25 C Liquid density at 25 C g/cm 3 Pale yellow liquid 7 Requirements 7.1 The requirements for hafnium amides for Tier A are listed in Table 4. 8 Grade 1 Procedures 8.1 This section does not apply to this chemical. 9 Grade 2 Procedures 9.1 This section does not apply to this chemical. 10 Grade 3 Procedures 10.1 This section does not apply to this chemical. 11 Grade 4 Procedures 11.1 This section does not apply to this chemical. 12 Tier A Procedures NOTE 2: Standardized test methods are being developed for all parameters at the purity level indicated. Until standardized test methods are published, test methodology shall be determined by user and producer Trace Metals Analysis The following method has given satisfactory results in determining trace metal impurities at the specified value for the elements listed in Table 4. Alternate methods may be used as long as method validation as per SEMI C1 can be demonstrated. Page 2

4 Mixed Acid Prepared by dilution of ultra pure 49% HF and 70% HNO 3 with appropriate weight of deionized water Standards Prepare multi-element standard solutions (calibration standards and quality control check standards) by diluting with mixed acid described in of appropriate weights for ICP-MS Sample Preparation Dispense approximately 0.1 ml of the Hafnium amide sample into a dry and clean PFA sample bottle and record the weight to at least 3 decimal places. Under hood, add 49% HF dropwise into the sample aliquot. The sample will react vigorously with the HF; allow the reaction to proceed until it subsides before adding the next drop. Repeat until an approximate total of 1 2 ml of HF has been added. Dilute the sample with an acid mixture containing H 2 O 2, HNO 3 and HF. The final dilution factor of the sample should be appropriate to minimize the space charge effects in the ICP-MS measurement of the sample. This dilution factor will be dependent on the type of ICP-MS used. NOTE 3: Do not mix 70% HNO 3 and 30% H 2 O 2 directly; make a prior dilution Analysis Analyze the samples by inductively couple plasma mass spectrometry (ICP-MS). Highresolution ICP-MS is suggested. It is recommended to run each sample in duplicate. In addition prepare a sample preparation blank for each analysis. It is also recommended to use an internal standard or a spiked sample solution to correct for the matrix effect Hydrocarbons Analysis The following method has provided satisfactory results in determining total hydrocarbons at the specified value using H-NMR Sample Preparation Under an inert atmosphere transfer 0.2ml of Hafnium amide into an NMR tube. Add 1ml of a solution of the internal standard (TMS) in deuterated benzene Analysis Calculate hydrocarbons from the integrations of peaks in the hydrocarbon region with that of the internal standard. For convenience hydrocarbons may be calculated as hexane Assay by NMR Ratio of the integration peaks from Hafnium amide to total integration of all peaks in the range -0.5 to 8ppm. 13 Tier B Procedures 13.1 This section does not apply to this chemical. 14 Tier C Procedures 14.1 This section does not apply to this chemical. 15 Tier D Procedures 15.1 This section does not apply to this chemical. Page 3

5 Table 4 Impurity Limits and Other Requirements for Hafnium Amides Previous SEMI Reference # -- Tier A (Guide) Assay ( 1 H NMR) 99% Hydrocarbons ( 1 H NMR) 1% Aluminium (Al) 500ppb Antimony (Sb) Arsenic (As) Barium (Ba) Boron (B) Cadmium (Cd) Calcium (Ca) Chromium (Cr) Copper (Cu) Iron (Fe) Lead (Pb) Lithium (Li) Magnesium (Mg) Manganese (Mn) Nickel (Ni) Potassium (K) Sodium (Na) Tin (Sn) Titanium (Ti) 10ppm Vanadium (V) Zinc (Zn) Zirconium (Zr) 2000ppm NOTICE: SEMI makes no warranties or representations as to the suitability of the standard(s) set forth herein for any particular application. The determination of the suitability of the standard(s) is solely the responsibility of the user. Users are cautioned to refer to manufacturer s instructions, product labels, product data sheets, and other relevant literature respecting any materials or equipment mentioned herein. These standards are subject to change without notice. By publication of this standard, (SEMI) takes no position respecting the validity of any patent rights or copyrights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of any such patent rights or copyrights, and the risk of infringement of such rights are entirely their own responsibility. Page 4