P50 controller described operational error at 8500 when he/she issued unrestricted climb to a departure conflicting with arrival traffic.

Narrative

I was working the Santan Radar sector during a moderate departure push when Aircraft X on a Stanfield 2 departure checked in and I issued a climb to FL210; when I should have done nothing more than simply radar identify the aircraft due to arrival traffic on the ARLIN arrival; another CRJ9. I experienced a lapse in memory and believed that the 2 aircraft would have separation since Aircraft X was going to level at 7;000 FT on the SID and fly underneath the arriving CRJ9. I called traffic to Aircraft X initially reference the arrival when the 2 aircraft were 8 miles apart and mistakenly told Aircraft X that the arrival was restriction above them (Aircraft X). Aircraft X had the other CRJ9 in sight at this point. After exercising several other control instructions; I was asked by the Handoff Specialist; 'What's going on with these two?' while physically pointing to Aircraft X and the CRJ9 on the arrival. After realizing that separation was lost or going to be lost imminently; I instructed Aircraft X to turn right heading 270 degrees immediately. The initial investigation has revealed that the minimum separation was 2.49 miles horizontally; 600 FT vertically. During my training on Santan; I developed a personal system of pre-marking my strips with the altitude I would climb the aircraft to on initial call-up. When the aircraft would check in; I would scan the strip and place a checkmark next to the pre-planned altitude as I was issuing it. In the past 3-4 months since working the sector on my own; I believe I have let up in my diligence of sticking to a personal system that I believe assisted me in ensuring separation. There were 3 minor distractions occurring at the time of this incident; a VFR overflight northwestbound at 10;500 FT that was a potential conflict for preceding Stanfield departures; and a MOBIE departure on which a Tower run down strip did not print; so the Santan Handoff Specialist was coordinating with the Local Controller at the time I mistakenly issued Aircraft X a climb to FL210. The last distraction was caused by my own arrogance when the Handoff Specialist made a comment that I should have climbed a preceding eastbound jet on the MAXXO 1 departure reference an ARLIN arrival that I was just not comfortable with climbing reference the ARLIN's indicated ground speed of 310 KTS and the proximity of the MAXXO 1 departure. I should not have let the Handoff Specialist's comment cause my pride and arrogance to swell up. Working departures out of Sky Harbor; I have found it is easy to get into a habit of automatically climbing everyone to FL210. Short of having eastbound departures fly 20 miles west on west flow; I don't think there is anything that can be done to eliminate the need to 'tunnel' departure aircraft underneath arrivals in this one specific flow/sector combination. I believe that I should have consistently followed my personally-developed system of pre-planning and pre-marking strips with the initial altitude to climb to and placement of a checkmark next to the pre-planned altitude upon my issuing it to the aircraft in order to ensure separation.