you can create an oscillator by this work. By this work you apply a positive feedback to this simple circuit. Take a look at attached file. In addition for more professional information you can refer to books related to VLSI such as Digital Integrated Circuits Rabaey 2nd Ed.
The gate will oscillate at its higest frequency – possible 4MHz to 10MHz
But O/P will not be square wave rather sine wave. Frequency will depend upon speed of CMOS IC used. ( which family of CMOS ) & It will not be same for all ICs. Being operated in linear region it will draw high power, this may damage the IC.
