TRIMETHYLSILYLDIETHYLAMINE 

AP001 

 

A SUPERIOR ADHESION PROMOTER FOR MICROELECTRONIC APPLICATIONS 

 

TMSDEA (AP001) is a superior adhesion promoter, providing highest coverage in short prime time at low temperature. It offers speed, higher contact angles, greater surface energy reduction and less undercut when compared to HMDS. AP001 is excellent for both negative and positive resist with a wide range of thin films, including silicon, doped and undoped polysilicon, silicon nitride, silicon oxides, PSG/BPSG, and various silicides. Under similar application conditions, AP001 typically gives 10° higher contact angles than HMDS. 

 

TMSDEA ELECTRONIC GRADE 

AP001 is used for vapor phase deposition in demanding applications with critical dimensions down to 0.3m m, or less. It has increased the effectiveness and throughput of in-line priming modules. 

TMSDEA has boiling point and vapor pressure characteristics virtually identical to HMDS. It may be used as a replacement for HMDS without equipment modification. The reaction by-product of TMSDEA is lower in toxicity than the HMDS reaction by-product. 

 

DESCRIPTION 

Trimethylsilyldiethylamine (TMSDEA) is a low viscosity organosilane used to promote superior adhesion of photoresists to various substrates. It is manufactured to meet the rigorous demands of today's microelectronics industry. 

REACTION MECHANISM 

AP001 is a surface modifying agent. It reacts rapidly in a stepwise fashion with various surfaces, such as silicon dioxide, metal oxides, nitrides, etc. The first in this sequence is the reaction of TMSDEA with surface adsorbed water. This reaction dramatically reduces the surface energy of the substrate, leaving it available for further reaction. The second step is the reaction of TMSDEA with the surface hydroxyls or oxides to afford a trimethylsiloxylated surface, thus preventing further adsorption of water or other polar materials. This reaction further reduces the surface energy and permits better surface coverage. Photoresists wet these primed surfaces more uniformly. Problems with dewetting and edge pullback are greatly reduced. Undercutting of resist during development is significantly lessened. The mechanism of interaction of AP001 with a typical hydroxylated surface, such as SiO2 may be depicted as follows:

 

AP001 is more reactive with substrates than HMDS. This increased reactivity is due to the increased basicity of the diethylamino moiety compared to HMDS. The increased basicity is attributed to the reduced sharing of the electron pair on the nitrogen atom with the silicon atom of the TMSDEA molecule. The increased basicity of the TMSDEA nitrogen makes the diethylamine a more basic group and, therefore, AP001 is a much more reactive material. This increased reactivity results in a greater number of trimethylsilyl groups bonded to the substrate surface in shorter contact times. Prime time is significantly reduced as compared to HMDS.

 

The coverage of a substrate is related to the number of trimethylsilyl groups bound to the surface. The trimethylsilyl groups reduce penetration of aqueous solutions such as developers and etchants. The greater the number of trimethylsilyl groups, the greater the contact angle, reducing the occurrence of undercutting. The trimethylsilyl groups on substrates do not increase the adhesion of photoresist use; rather they block penetration of liquids between the substrate and the photoresist. 

Contact angle measurement is a recognized method of determining the degree of silylation coverage of a substrate. The higher the contact angle, the greater the number of trimethylsilyl groups on a surface. Higher contact angles reduce undercut. There will be less undercut as measured by the ratio of horizontal and vertical etch at a given point the greater the contact angle. The optimum contact angle for most substrates is 65-75° Below 60° the blocking action of the trimethylsilyl group is insufficient and lifting can occur. Contact angles higher than 75° can lead to dewetting and/or blistering of resist. Blistering it is believed is due to accumulation of nitrogen between resist and substrate which produces this phenomenon due to lowered surface energy. AP001 will nearly completely silylate a silicon surface. Complete silylation is prevented due to the steric requirements of the trimethylsilyl groups. 

 

APPLICATION METHODS

TMSDEA can be applied to substrates by several techniques, including vapor prime, spinning, spraying or dipping. The recommended method of application is via vapor techniques. AP001 is especially suited to vapor deposition systems and will produce environmentally stable primed substrate having excellent and uniform coverage. This efficient method of application offers rapid, uniform, reproducible priming of substrates with a minimum quantity of AP001. 

AP001 is specifically designed for in-line priming applications where ideal priming time is less than 20 sec. The greater reactivity of AP001 versus HMDS increases the effectiveness and efficacy of in-line equipment and dramatically increases throughput. The preferred degree of silylation (as measured by contact angles of 65-75°) is typically achieved in 5-15 sec. at 50°C. Higher degrees of silylation (75-78°) are achieved in 10-1 5 sec. at 130°C. Higher temperatures (e.g. 150°C) can result in contact angles of 85° or greater in less than 10 seconds. In general, it is recommended to hold temperature constant at 50°C and vary the prime time with different substrates to achieve the desired contact angle and degree of silylation. 

Due to the diversity of application methods, plant locations and photoresists compatible with AP001, please consult with our technical staff for applications assistance. 
 

PACKAGING 

AP001 is available in 4 oz., 1 pint and1 quart sizes. AP001 is packaged in glass bottles under Class 10 conditions and is filtered to 0.2m m. Because AP001 will react with moisture in the air, smaller quantities are recommended if your usage is limited or vapor prime methods are being employed. Custom blends of AP001 in various solvents and materials can be formulated. Specialized containers for track and bubbler applications are available. Please contact our customer service department. 

SHELF LIFE 

AP001 is stable for six months in unopened containers. It will react with atmospheric moisture. Exposure to the environment should be limited to preserve purity and shelf life. Resealing opened containers under dry nitrogen will lengthen shelf life. 

 

PROPERTY PROFILE 

Product No. 

AP001

Product Name:

Trimethylsilyldiethylamine

Synonym:

TMSDEA (DEATS)

Structure Formula:

(CH3) SiN (C2H5)2

Emperical Formula:

C7H19NSi

Molecular Weight:

145.3

Boiling Point:

126-7°C

Freezing Point:

-10°C

Density (d420):

0.763 

Refractive Index nd (25°C):

1.4410

Flashpoint:

10°C

 

PRODUCT SPECIFICATIONS 

Composition: 98%

Residue: 10ppm max.

Chloride: <2.0ppm (maximum) 

Infrared: Matches standard spectrum

Filtered to 0.2m m 

 

 

 
 

References 

Yanazawa, H., Coll. of Surfaces, 1984, (19) 133. 

Michielsen, M.C.B.A., Marriott, V.B., Ponjee, J.J., Van der Wel, H., Touwslager, F.J., Moonen, J.A., H.M.; Microelec. Eng. 1990, (11) 475-480.

Moreau, W.M., Semiconductor Lithography, Principles, Practices & Materials, Plenum Press, N.Y., N.Y. (1988)..,

Nistier, J.L KTIMicroelectronics Seminar, 1988, 233.