How to do low voltage chip test work

[leonken]

I want to test a chip. One of the output pin is a DC reference voltage, the quantity of the reference voltage is 200 mV.
The input impedance of multimeter is 10 meg.
And I found that when i connecte the multimeter directly to the pin. the voltage will increas.
So, I insert a big resistor(10 meg) into the pin and the multimeter. the reference voltage become much smaller.
How to accurately test the voltage?

 

[hermin]

if your connecting a voltmeter and an ohmmeter on the sam device, the voltage may increase because the ohmmeter works by applying voltage on the device and measuring the current to get the resistance, so i think that it goes up because of the ohmmeter

 

[leonken]

if your connecting a voltmeter and an ohmmeter on the sam device, the voltage may increase because the ohmmeter works by applying voltage on the device and measuring the current to get the resistance, so i think that it goes up because of the ohmmeter

In general, how large is the internal voltage of the multimeter? 1V or 0.5 V?

Thank you for your replay.
I simulated the circuit with the equivalent circuit of multimeter. I can get the similar result compared with test results.
And the most important thing is how to solve this problem.
What kind of test method and equipment should I adopt?
thanks!!!1