Nitroxyl

Example 2

This example was conducted to determine the effect of HALS compounds to the pattern profile. The aforementioned quenchers (i.e., HALS compounds) 4-methoxy-TMP-1-oxy free radical, 4-hydroxy-TMP and 4-hydroxy-TMP-1-oxy free radical, 4-benzoate-TMP-1-oxy free radical, 4-acetoamide-TMP-1-oxy free radical and Tinuvin® 123 were used as a base quencher in an iCAR photoresist.

The nomenclature for this example is shown in the Table 1a.

Table 2 shows the formulation (compositions) for the i-line chemical amplification photoresist (iCAR) samples. HALS analogs were used as base quenchers. The amount of quencher was chosen such that the quencher/PAG molar ratio was 0.139. TINUVIN-123 (See formula 6) contains two parts of the piperidine structure (See formula 1). It is therefore expected that the effect of the compound of formula-1 (from TINUVIN-123) is twice that of the other compounds. TINUVIN-123 was therefore tested at half the amount of the other base quenchers (the quencher loading of TINUVAN-1123 was adjusted to have a quencher/PAG molar ratio of 0.069.

Preparation of Sample #1

90 grams (g) of Polymer-A (a copolymer of p-hydroxy styrene (PHS)/tert-butyl acrylate (TBA) of 64/36 molar ratio, weight average molecular weight Mw=23,000 g/mole obtained from Maruzen Petrochemical Co., LTD.) and 10 g of Polymer-B (a copolymer of PHS/styrene (STY)/TBA in a 66/19/15 molar ratio, (weight average molecular weight Mw=11,000 g/mole obtained from DuPont Electronic Polymer) was taken in a 500 milliliters (ml) plastic bottle. Against 100 parts of polymer, 1 part (1 g) of NHNI-PFBS (obtained from Toyo Gosei Co. LTD, Mw=495.27), 0.048 part (0.048 g) of 4H-TEMPO (weight average molecular weight Mw: 172.25 g/mole) and 1 part (1 g) of PIONIN ME-400 obtained from Takemoto Oil and Fat.) were added. Against a total of 102.048 g of material, 117 g of solvent mixture that consist of 95% of PMGEA (111.2 g) and 5% of GBL (5.8 g) were added to adjust the solids content to 46.5 wt %.

The ingredients used to manufacture Sample #1 were mixed on a roller shaker. The quencher (4H-TEMPO) and PAG (NHNI-PFBS) molar ratio is calculated as follows:
(0.0489 g/172.25)/(1 g/495.27)=0.139Preparation of Samples #2 to #5

Samples #2 to #5 were prepared the same manner as Sample #1 and uses the same quencher/photoacid generator molar ratio. The only difference is the type of quencher used (as may be seen in Table 2 below). The quencher loading was adjusted to have the same quencher/PAG molar ratio (0.139) as that shown in the Example 2.

Sample #6

Sample #6 was prepared in the same manner as Sample #1 except for the type of quencher and the quencher/PAG molar ratio. The quencher was TINUVIN-123. For this sample, the quencher loading was adjusted to have a quencher/PAG molar ratio of 0.069.

All weights in Table 2 are in parts per hundred based on 100 parts of the Polymer A and Polymer B, except for the solids content, which is expressed in weight percent.

From the data obtained, it was seen that Sample #2 and #4 produced an overhung profile. An overhung profile is one where the sidewall angle is larger than 90° (degrees). In other words, when the width is compared at the surface and bottom of the photoresist pattern using a scanning electron microscopy cross-sectional image, the width at the surface is narrower than that at the bottom.

Other samples gave favorable entrance profiles. Thermal weight loss of 4H-TEMPO was better than 4H-TEMP and 4-methoxy-TEMPO. TINUVIN-123 also indicated no weight loss at up to 190° C., but Sample #6 indicated an angled sidewall. From these test results, it can be concluded that the favorable pattern profile is not dependent on the volatility of base quencher. For example, a quencher that has piperidine 1-oxyl structure gave a favorable profile regardless of substitution of the 4 position, except for the 4-acetamide-TEMPO. FIG. 7 shows a comparison of HALS analogues on a pattern profile of 25 μm (micrometers) for a 1:1 contact hole.

Without being limited to theory, it is believed that the overhung profile is produced because during the initial step, the fluorinated naphtalimide photoacid generator is cleaved by incident UV light. Then the chromophore part of intermediate, Chromophore Intermediate-1 forms Chromophore Intermediate-2 by a ring-opening reaction as shown in the FIG. 2.

The I-line exposure process and post exposure bake (PEB) process is conducted in an ambient atmosphere. This results in the presence of oxygen at the surface of the photoresist. Oxygen penetrates into the photoresist at the exposed surface. The highest oxygen concentration therefore exists at the surface of the photoresist. The depth of the penetration of oxygen into the photoresist depends on its polymer matrix composition, the solvent system used and/or the process conditions used.

At the surface, the Chromophore Intermediate-2 is scavenged by oxygen. The effect is known as the Oxygen Inhibition Effect. After the Intermediate-2 is scavenged, hydrolysis may not proceed. Thus the acid intermediate, the perfluoroalkylsulfonyl radical, does not abstract hydrogen from the hydrolyzed radical. As a result, the concentration of photo acid at the surface is lower than at the middle or bottom of the photoresist. This leads to a cross-sectional width (diameter) that is narrower at the surface than that at the bottom. This mechanism is shown in the FIG. 2. FIG. 2 depicts a reaction scheme for the proposed mechanism of the overhung profile by adopting Norish-1 cleavage model of acid generation for fluorinated naphtalimide photoacid generators.

When a TEMPO free radical is used in a photoresist, the Chromophore Intermediate-2 is scavenged by the TEMPO free radical to form a nitroxyl alkyl intermediate (NOR-TEMPO). As discussed above, the Chromophore Intermediate-2 is also scavenged by oxygen. The NOR-TEMPO and the oxidized intermediate regenerates the TEMPO free radical along with a proton. In this model, the generated proton is coupled with the acid part of intermediate to then generate a photo acid. It is believed that this reaction occurs where the oxygen concentration is high. Thus, TEMPO free radical or TINUVIN-123 (NOR-TEMPO) indicated favorable profile.

In this proposed mechanism, the nitroxy structure of TEMPO plays a significant role. Thus, the 4H-TEMP (4-hydroxy-1,2,2,6,6-pentamethylpiperidine) indicates an overhung profile. However, 4-acetoamide-TEMPO (4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl free radical), that has the nitroxyl structure, improves the overhung profile. FIG. 3 depicts a reaction scheme for the proposed mechanism for a top rounding profile using TEMPO as scavenger.

Example 3

Nitrous oxide (N₂O) is produced via the dimerization and dehydration of HNO, and is the most common marker for nitroxyl production (Fukuto et al., Chem. Res. Toxicol. 18:790-801 (2005)). Nitroxyl, however, can also be partially quenched by oxygen to provide a product that does not produce N₂O (see Mincione et al., J. Enzyme Inhibition 13:267-284 (1998); and Scozzafava et al., J. Med. Chem. 43:3677-3687 (2000)). Using either nitrous oxide gas or Angeli's salt (AS) as a standard, the relative amounts of N₂O released from compounds of the disclosure was examined via gas chromatography (GC) headspace analysis.

A procedure for determining the relative amounts of N₂O released from compounds of the disclosure is as follows. GC was performed on an Agilent gas chromatograph equipped with a split injector (10:1 splitting), microelectron capture detector, and a HP-MOLSIV 30 m×0.32 mm×25 μm molecular sieve capillary column. Helium was used as the carrier (4 mL/min) gas and nitrogen was used as the make-up (20 mL/min) gas. The injector oven and the detector oven were kept at 200° C. and 325° C., respectively. All nitrous oxide analyses were performed with the column oven held at a constant temperature of 200° C.

All gas injections were made using an automated headspace analyzer. Vial pressurization was 15 psi. The analyzer's sample oven, sampling valve, and transfer line were kept at 40° C., 45° C., and 50° C., respectively. The oven stabilization, vial pressurization, loop fill, loop equilibration, and sample injection times were 1.00 min., 0.20 min., 0.20 min., 0.05 min., and 1.00 min., respectively.

All determinations used a batch of nominal 20 mL headspace vials with volumes pre-measured for sample uniformity (actual vial volume varied by ≤2.0% relative standard deviation (n=6)). The average vial volume for the batch was determined from six randomly-selected vials by calculating the weight difference between the capped and sealed empty (i.e., air-filled) vial and the capped and sealed deionized water-filled vial using the known density of deionized water, then averaging. Blanks were prepared by sealing and capping two vials then purging each for 20 seconds with a gentle argon stream. Nitroxyl standards were prepared by sealing and capping four vials then purging each for 1 minute with a gentle stream, from a gas cylinder, of a 3000 ppm nitroxyl standard.

CXL-1020 (N-hydroxy-2-methanesulfonylbenzene-1-sulfonamide) “standards” were prepared by, in duplicate, accurately weighing 10±0.5 mg of CXL-1020 and adding it to each 4 mL vial. Using an auto pipette, 1 mL of argon-purged anhydrous DMF (Sigma-Aldrich) was added to each 4 mL vial to form a CXL-1020 stock solution for each sample and the vials were capped and shaken and/or sonicated to insure complete dissolution upon visual observation. Using an auto pipette, 20 mL vials were charged with 5 mL of PBS (purged for at least 30 min. with argon prior to use), purged with argon for at least 20 sec., and sealed with a rubber septum. Using a 50 μL syringe, 50 μL of the CXL-1020 stock solution was injected into each 20 mL vial containing the PBS.

Samples were prepared as follows. In duplicate, 18±1 mg of each sample was accurately weighed into each 4 mL vial. Using an auto pipette, 1 mL of argon-purged anhydrous DMF was added to each 4 mL vial to form a sample stock solution for each sample and the vials were capped and shaken and/or sonicated to insure complete sample dissolution upon visual observation. Using an auto pipette, 20 mL vials were charged with 5 mL of PBS (purged for at least 30 min. with argon prior to use), purged with argon for at least 20 sec., and sealed with a rubber septum. The vials were equilibrated for at least 10 min. at 37° C. in a dry block heater. Thereafter, using a 50 μL syringe, 50 μL of a sample stock solution was injected into each 20 mL vial containing the PBS. The vials were then held at 37° C. in the dry block heater for a time period such that the sum of the time spent in the dry block heater plus the time spent in the automated headspace analyzer oven before sample injection equaled the desired incubation time.

The sequence for auto-injection was as follows: blank replicate 1, blank replicate 2, N₂O standard replicate 1, N₂O standard replicate 2, CXL-1020 standard replicate 1, CXL-1020 standard replicate 2, sample 1 replicate 1, sample 1 replicate 2, sample 2 replicate 1, sample 2 replicate 2, etc., concluding with N₂O standard replicate 3, and N₂O standard replicate 4. An EXCEL spreadsheet is used for inputting data thus determined and calculating, for each sample, the relative N₂O yield in percent for each incubation time. The results obtained are provided in Table 2.

For compounds of formulas (3) and (4), determinations are as described above except enzyme activated samples are also prepared as follows: (i) accurately weigh 50 mg of porcine liver esterase (PLE, E3019-20KU, crude, Sigma-Aldrich) into a 20 mL headspace vial; (ii) using an auto pipette, 5 mL of argon-purged anhydrous PBS is added to form a PLE stock solution; (iii) the vial is capped and shaken to insure complete dissolution upon visual observation; (iv) samples of nitroxyl donors are prepared as disclosed above except 4.75 mL of PBS is added instead of 5 mL; and (v) using an auto pipette, the 20 mL vials are then charged with 250 μmL of PLE stock solution prior to sample addition. The sequence for auto-injection is as follows: blank replicate 1, blank replicate 2, N₂O standard replicate 1, N₂O standard replicate 2, CXL-1020 standard replicate 1, CXL-1020 standard replicate 2, sample 1 (no PLE) replicate 1, sample 1 (no PLE) replicate 2, sample 1 (with PLE) replicate 1, sample 1 (with PLE) replicate 2, sample 2 (no PLE) replicate 1, sample 2 (no PLE) replicate 2, sample 2 (with PLE) replicate 1, sample 2 (with PLE) replicate 2, etc., concluding with N₂O standard replicate 3, and N₂O standard replicate 4.

Another procedure for determining the relative amounts of N₂O released from compounds of the disclosure is as follows. GC is performed on a Varian CP-3800 instrument equipped with a 1041 manual injector, electron capture detector, and a 25 m 5 Å molecular sieve capillary column. Grade 5.0 nitrogen is used as both the carrier (8 mL/min) and the make-up (22 mL/min) gas. The injector oven and the detector oven are kept at 200° C. and 300° C., respectively. All nitrous oxide analyses are performed with the column oven held at a constant temperature of 150° C. All gas injections are made using a 100 μL gas-tight syringe with a sample-lock. Samples are prepared in 15 mL amber headspace vials with volumes pre-measured for sample uniformity (actual vial volume ranges from 15.19 to 15.20 mL). Vials are charged with 5 mL of PBS containing diethylenetriamine pentaacetic anhydride (DTPA), purged with argon, and sealed with a rubber septum. The vials are equilibrated for at least 10 minutes at 37° C. in a dry block heater. A 10 mM stock solution of AS is prepared in 10 mM sodium hydroxide, and solutions of the nitroxyl donors are prepared in either acetonitrile or methanol and used immediately after preparation. From these stock solutions, 50 μL is introduced into individual thermally-equilibrated headspace vials using a 100 μL gas-tight syringe with a sample-lock to provide final substrate concentrations of 0.1 mM. Substrates are then incubated for 90 minutes or 360 minutes. The headspace (60 μL) is then sampled and injected five successive times into the GC apparatus using the gas-tight syringe with a sample lock. This procedure is repeated for two or more vials per donor.