74HC14 waveform question
When trace and wires are inductive at the rate up to 10nH/cm interact with the scope probe coax and standard ground leads, any measurements with rise times faster than what the 20MHz filter allows will have impedance mismatch faulty signals, both due to the board design and the scope probe ground lead.

Either apply the 20MHz DSO filter at all times or learn how to capture proper signals and learn the effects of the [robe tip capacitance.  It is no secret that Nch low side drivers are much lower impedance than Pch High side drivers and breadboards without a ground plane closer than trace width the chances of matched impedance on traces is zero. Thus overshoot depends on the degree of how much lower the driver impedance is.

If you want any chance of getting a clean signal; the ground plane, IC decoupling cap and output must all be within 1cm be probed as below Also any long traces or loads examined for reflection effects.

Recall 80% Tr = 0.35/f (-3dB) so Tr=0.35/20MHz =17.5ns 


  This means any rise times &lt; 18 ns common to all 74HCxx CMOS will be inaccurate on a scope   unless you follow this test method... or ignore it and apply the 20MHz DSO filter switch.




Getting rid of noises after RC low pass filter stage